Master the board step 3

Pulmonology
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Chemistry: Increased serum bicarbonate is metabolic compensation for
respiratory acidosis.
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ABG: Should be done even in office-based cases to assess CO 2 retention
and the need for chronic home oxygen based on pO 2 (you expect the pCO 2
to rise and the pO 2 to fall).
Basic Science Correlate
Mechanism of Right Heart Enlargement in COPD
Hypoxia in the lungs causes capillary constriction, in which precapillary
sphincters in the lungs constrict to shunt blood away from hypoxic areas
of the lung. Since the hypoxia of COPD is global throughout the lung, this
diffuse vasoconstriction increases pressure in the right ventricle and right
atrium. Over time, the result is hypertrophy of both chambers, leading to
cor pulmonale, or right heart failure.
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Pulmonary function testing (PFT): You should expect to find the following:
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Decrease in FEV 1
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Decrease in FVC from loss of elastic recoil of the lung
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Decrease in the FEV 1 /FVC ratio
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Increase in total lung capacity from air trapping
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Increase in residual volume
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Decrease in diffusion capacity lung carbon monoxide (DLCO) caused by
destruction of lung interstitium
PFT Results: COPD
FEV 1 FVC FEV 1 /FVC ratio
Total Lung
Capacity
Residual
Volume
DLCO
↓ ↓ ↓ ↑ ↑ ↓
Chronic Medical Therapy of COPD
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Tiotropium or ipratropium inhaler
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Albuterol inhaler
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Pneumococcal vaccine: Heptavalent vaccine, Pneumovax
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Influenza vaccine: Yearly. Inactivated injections only.
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Smoking cessation
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Long-term home oxygen if the pO 2 < 55 or the oxygen saturation is
< 88 percent
Almost all patients with
COPD can tolerate beta-1-
specific blockers.
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